A pressurized-water coolant reactor installation ordinarily includes the reactor pressure vessel, a steam generator containing a heat exchanger through which the coolant from the vessel is circulated, and a coolant pump which draws or sucks the coolant from the heat exchanger's outlet and discharges it to the pressure vessel via a pipe line which forms a loop with one leg going from the vessel to the steam generator and the other leg, via the coolant pump, returning to the vessel.
The steam generator has a vertical housing with its lower portion closed by a tube sheet in which the inlet and outlet legs of an inverted U-shaped tube bundle heat exchanger are mounted, the housing below this tube sheet being partitioned to form inlet and outlet manifolds for the inlet and outlet ends of the heat exchanger. Ordinarily, a pipe from the vessel connects with the inlet manifold and a separate pipe connects the outlet manifold with the pressure vessel via the coolant pump.
The Michel U.S. Pat. No. 3,966,549, dated June 29, 1976, relates to an improvement wherein the coolant pump is built into the housing below the steam generator's tube sheet so that the loop piping is formed by a single pipe internally divided to carry the coolant from the pressure vessel to the steam generator and from the steam generator back to the vessel.
According to that Michel patent, the internal division is effected by the pipe being internally divided into the two necessary conduits by a transverse partition wall extending longitudinally for the length of the pipe inside of the pipe and having side edges welded to the inside of the pipe. It is suggested that this partition wall have a transverse curvature so that it is laterally deformable by bowing when the pipe thermally changes in diameter.
The temperature of the coolant carried by the pipe may range from a cold or reactor shutdown temperature of about 20.degree. up to reactor operating temperatures of 350.degree. C, and the integrity of the partition wall must be maintained throughout the consequent range of pipe diameter changes due to thermal expansion and contraction of the pipe.